This disclosure relates to the field of wireless telecommunications especially in the field of cellular telephony, and more particularly to a cellular repeater and its method of operation and especially for frequency selective operation.
Cellular telephony in the United States operates on the 850 MHz and 1900 MHz bands and other bands are also coming into use. Each of these bands are divided into channels and each channel is able to carry a large number of separate telephony signals where each signal is centered on a specific UHF frequency. More than one user is able to use a frequency simultaneously since multiplexing is able to allow frequency sharing. Multiplexing today includes: time domain, frequency domain and CDMA (code division multiple access). All three are used in the cellular phone service industry.
Cell phones automatically capture and switch their operation to a specific frequency and multiplexing protocol that is identified to it by a base station during a handshake process. Because of mobility, the cell phone may be handed-off frequently to a different base station which may require a change in the frequency used, i.e., another handshake. The frequency of use and multiplex protocol is stored in cell phone memory.
Cellular repeaters are bidirectional amplifiers and are widely used for cellular traffic. They improve signal strength in low signal zones such as building interiors and outlying areas. This results in fewer dropped calls and improved cell phone battery life due to lower power requirement. Currently in the market place, there are two common types of repeaters. The first type is a low cost consumer-grade repeater. This repeater is broad band and amplifies all received signals which adds greatly to the noise background in any one of the signals. The second type is a commercial-grade, higher-cost, so-called “off-the-air” repeater which is usually dedicated to a specific commercial carrier. The present disclosure describes a system and method of operation that combines low-cost and mobility while achieving low noise and specific channel selection and isolation.